bisecting fixing commit since 19bb613acb9ad8e57593cad5118acaee117cc303
building syzkaller on 7516d9fa9301d2dfa5beaf49d93563f8048694aa
testing commit 19bb613acb9ad8e57593cad5118acaee117cc303 with gcc (GCC) 8.1.0
kernel signature: 3da26e15647e00f8386f2eeb649bd1df8e365099
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
testing current HEAD 672481c2deffb371d8a7dfdc009e44c09864a869
testing commit 672481c2deffb371d8a7dfdc009e44c09864a869 with gcc (GCC) 8.1.0
kernel signature: b9c602fa9506d24f631ba3d82993bf85f2601f90
all runs: crashed: KASAN: slab-out-of-bounds Read in bacpy
revisions tested: 2, total time: 23m25.245822145s (build: 16m26.183641504s, test: 6m15.444667272s)
the crash still happens on HEAD
commit msg: Linux 4.19.91
crash: KASAN: slab-out-of-bounds Read in bacpy
IPv6: ADDRCONF(NETDEV_UP): veth0_to_hsr: link is not ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_hsr: link is not ready
==================================================================
hsr0: Slave B (hsr_slave_1) is not up; please bring it up to get a fully working HSR network
BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:348 [inline]
BUG: KASAN: slab-out-of-bounds in bacpy+0xe/0x10 include/net/bluetooth/bluetooth.h:236
Read of size 6 at addr ffff8880950674fb by task kworker/u5:2/6925

CPU: 0 PID: 6925 Comm: kworker/u5:2 Not tainted 4.19.91-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci1 hci_rx_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:348 [inline]
 bacpy+0xe/0x10 include/net/bluetooth/bluetooth.h:236
 hci_inquiry_result_with_rssi_evt net/bluetooth/hci_event.c:3951 [inline]
 hci_event_packet+0x1cf6/0x9e18 net/bluetooth/hci_event.c:5832
 hci_rx_work+0x34f/0x8a0 net/bluetooth/hci_core.c:4352
 process_one_work+0x835/0x1670 kernel/workqueue.c:2153
 worker_thread+0x85/0xb60 kernel/workqueue.c:2296
 kthread+0x327/0x3f0 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415

Allocated by task 6927:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc_node mm/slab.c:3689 [inline]
 __kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3703
 __kmalloc_reserve.isra.39+0x2c/0xc0 net/core/skbuff.c:137
 __alloc_skb+0xd7/0x580 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:995 [inline]
 bt_skb_alloc include/net/bluetooth/bluetooth.h:339 [inline]
 vhci_get_user drivers/bluetooth/hci_vhci.c:180 [inline]
 vhci_write+0xa8/0x3f0 drivers/bluetooth/hci_vhci.c:299
 call_write_iter include/linux/fs.h:1820 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x44b/0x890 fs/read_write.c:487
 vfs_write+0x150/0x4d0 fs/read_write.c:549
 ksys_write+0x103/0x260 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x6e/0xb0 fs/read_write.c:608
 do_syscall_64+0xd6/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff888095067300
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 507 bytes inside of
 512-byte region [ffff888095067300, ffff888095067500)
The buggy address belongs to the page:
page:ffffea00025419c0 count:1 mapcount:0 mapping:ffff88812c35e940 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffffea00026614c8 ffffea0002539c48 ffff88812c35e940
raw: 0000000000000000 ffff888095067080 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888095067400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888095067480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888095067500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff888095067580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888095067600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================